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BIO130 > Lecture 6 > Flashcards

Lecture 6 Flashcards

1
Q

how many nucleotides are in a codon?

A

three

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2
Q

how many amino acids are there?

A

20

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2
Q

what is the concept of redundancy?

A

having multiple codons for one amino acid

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3
Q

what is the reading frame?

A

it is a way of dividing the nucleotides into sets of three

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4
Q

what is the mediator between mRNA and the protein sequence?

A

tRNA

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5
Q

how is redundancy managed? (2)

A

having more than one tRNA for the same amino acid

having tRNA that can base pair with more than one codon

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6
Q

where can ribosomes be found? (2)

A

on endoplasmic reticulum

in cytosol

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6
Q

what are ways of ensuring accuracy when matching with the genetic code? (3)

A

aminoacyl-tRNA synthetase

base pairing

aminoacyl tRNA synthetase correcting by hydrolytic editing

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7
Q

how is transfer RNA recognized? (3)

A

identifying the anticodon of the tRNA

recognizing the sequence on the acceptor’s arm

reading nucleotides on other positions on tRNA

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8
Q

How does the energy stored in the P site’s covalent bond between an amino acid and tRNA contribute to the energetically favourable peptide synthesis process?

A

makes peptide synthesis
energetically favourable

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9
Q

what is a ribozyme?

A

a ribosome with catalytic properties

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10
Q

what is the function of EF-Tu (EF1 in euk.)?

A

Checks
aminoacyl tRNA

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11
Q

what happens to EF-Tu if the base pairing is not correct?

A

not released

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12
Q

what happens to peptide bonds if the base pairing is not correct?

A

they will not form

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13
Q

what happens if the base pairing is correct? (2)

A

GTP is hydrolyzed

ET-Tu released

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14
Q

what is the purpose of the slight delay before the formation of p.p
bond?

A

allows one last check for accurate base-pairing

15
Q

what is the function of EF-G (EF2 in euk.)

A

helps the ribosome to move the mRNA
forward one codon at a time

helps speed up elongation of the
polypeptide chain

16
Q

Can ribosomes perform protein synthesis without the aid of elongation factors?

A

Yes, but…..slower and inefficient

17
Q

what is the role of elongation factors? (2)

A

improving speed and efficiency

error checking

18
Q

what is elongation mediated by?

A

GTP hydrolysis and release of EF-Tu & EF-G

19
Q

what does Polycistronic mean?

A

a type of mRNA molecule that carries the genetic information for multiple proteins

20
Q

what is the role of Shine-Dalgarno sequences during translation initiation in prokaryotes?

A

bind directly to the small ribosomal subunit’s mRNA-binding site.

21
Q

What is the significance of initiation factors (IFs) towards ribosomes during translation initiation?

A

IFs help position the small ribosomal subunit to the initiating AUG codon on mRNA

22
Q

During translation initiation, when does the large ribosomal subunit bind to the complex?

A

After initiation factors have dissociated

22
Q

What is the typical spacing of nucleotides observed during protein synthesis?

A

Every 80 nucleotides

23
Q

Which molecule binds to the initiator codon (AUG) during translation initiation?

A

Methionine tRNA

24
Q

what is the function of the human translation release factor?

A

terminating translation by recognizing stop codons

25
Q

Which are examples of molecular chaperones involved in protein folding?

A

Hsp60 and Hsp70

26
Q

what is the function of chaperone proteins?

A

helps proteins fold

27
Q

Which types of post-translational modifications are commonly observed in proteins?

A

Phosphorylation and glycosylation

28
Q

What is the purpose of covalent modifications in proteins?

A

To make the protein active or to recruit it to the correct membrane or organelle

29
Q

What is the cellular structure responsible for degrading proteins tagged with ubiquitin?

A

Proteasome

29
Q

What cellular process targets proteins for degradation when they are tagged with ubiquitin?

A

Proteasomal degradation

30
Q

Which enzymes are responsible for degrading proteins within the proteasome?

A

Proteases

30
Q

what do many antibiotics act on?

A

ribosomes

BIO130 (6 decks)

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